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Streamflow, Water Quality, and Contaminant Loads in the Lower Charles River Watershed, Massachusetts, 1999–2000

By ROBERT F. BREAULT, JASON R. SORENSON, and PETER K. WEISKEL

Water-Resources Investigations Report 02-4137

ABSTRACT

Streamflow data and dry-weather and stormwater water-quality samples were collected from the main stem of the Charles River upstream of the lower Charles River (or the Basin) and from four partially culverted urban streams that drain tributary subbasins in the lower Charles River Watershed. Samples were collected between June 1999 and September 2000 and analyzed for a number of potential contaminants including nitrate (plus nitrite), ammonia, total Kjeldahl nitrogen, phosphorus, cadmium, chromium, copper, lead, and zinc; and water-quality properties including specific conductance, turbidity, biochemical oxygen demand, fecal coliform bacteria, Entero-coccus bacteria, total dissolved solids, and total suspended sediment. These data were used to identify the major pathways and to determine the magnitudes of contaminants loads that contribute to the poor water quality of the lower Charles River. Water-quality and streamflow data, for one small urban stream and two storm drains that drain subbasins with uniform (greater than 73 percent) land use (including single-family residential, multifamily residential, and commercial), also were collected. These data were used to elucidate relations among streamflow, water quality, and subbasin characteristics.

Streamflow in the lower Charles River Watershed can be characterized as being unsettled and flashy. These characteristics result from the impervious character of the land and the complex infrastructure of pipes, pumps, diversionary canals, and detention ponds throughout the watershed. The water quality of the lower Charles River can be considered good—meeting water-quality standards and guidelines—during dry weather. After rainstorms, however, the water quality of the river becomes impaired, as in other urban areas. The poor quality of stormwater and its large quantity, delivered over short periods (hours and days), together with illicit sanitary cross connections, and combined sewer overflows, results in large contaminant loads that appear to exceed the river’s assimilative capacity.

Annual contaminant loads from stormwater discharges directly to the lower Charles River are large, but most dry-weather and stormwater contaminant loads measured in this study originate from upstream of the Watertown Dam and are delivered to the lower Charles River in mainstem flows. An exception is fecal coliform bacteria. Stony Brook, a large tributary influenced by combined sewer overflow, contributed almost half of the annual fecal coliform load to the lower Charles River for Water Year 2000. Much of this fecal coliform bacteria load is discharged from Stony Brook to the lower Charles River during rain-storms. Estimated stormwater loads for future conditions suggest that sewer separation in the Stony Brook Subbasin might reduce loads of constituents associated with sewage but increase loads of constituents associated with street runoff.

The unique environment offered by the lower Charles River must be considered when the environmental implications of large contaminant loads are interpreted. In particular, the lower Charles River has low hydraulic gradients, a lack of tidal flushing, a lack of natural uncontaminated sediment from erosion of upstream uncontaminated soils, and an anoxic, sulfide-rich bottom layer that forms a non-tidal salt wedge in the downstream part of the lower Charles River. Individually and in combination, these characteristics may increase the likelihood of adverse effects of some contaminants on the water, biota, and sediment of the lower Charles River.

CONTENTS

Abstract

Introduction

Purpose and Scope

Acknowledgments

Field Methods

Collection of Streamflow Data

Water-Quality Sampling

Cleaning of Sampling Equipment

Dry-weather Sampling

Stormwater Sampling

Sample Collection, Instrumentation, and Programming

Sample Retrieval and Processing

Continuously Monitored Water-Quality Properties

Data-Analysis Methods

Dry-Weather Mean Concentrations and Stormwater Event Mean Concentrations

Annual Loads for Water Year 2000

Dry Weather

Stormwater

Design-Storm Loads

Rainfall-Data Analysis

Quality Assurance

Streamflow

Charles River at Watertown (01104615)

Single-Family Land-Use Station (01104630)

Laundry Brook Station (01104640)

Faneuil Brook Subbasin

Multifamily Land-Use Station (01104673)

Commercial Land-Use Station (01104677)

Muddy River Subbasin

Stony Brook Subbasin

Water Quality

Indicator Bacteria

Nutrients

Trace Metals

Water-Quality Properties

Comparison between Stormwater Concentrations from This Study and Those from Other Studies

Contaminant Loads and Yields

Annual Loads

Fecal Coliform Bacteria

Enterococcus Bacteria

Nitrogen

Phosphorus

Trace Metals

Biochemical Oxygen Demand

Total Dissolved Solids

Total Suspended Solids

Annual Yields

Charles River at Watertown

Laundry Brook Subbasin

Faneuil Brook Subbasin

Muddy River Subbasin

Stony Brook Subbasin

Ungaged Areas

Uniform Land-Use Subbasins

Design Storm Loads

Estimated Stony Brook Subbasin Loads after Sewer Separation

Environmental Implications of Loads

Summary

References Cited

FIGURES

1. Map showing the location of tributary subbasins, major streams, and sampling stations in the lower

Charles River Watershed, Massachusetts

2. Photograph of the inside of typical gaging station used in this study of the lower Charles River

Watershed showing ( A ) a Dual valve Safe Purge II nitrogen gas system and (B) an ISCO automated

sampler, datalogger, and 26-ampere-hour sealed rechargeable battery

3. Typical hydrograph with distribution of flow-proportional stormwater samples, lower Charles River

Watershed

4. Hydrographs showing modeled discharge and dates of dry-weather and stormwater sampling, lower

Charles River Watershed, Water Year 2000

5. Map showing Thiessen polygons used to assign rain gages to subbasins in the lower Charles River

Watershed

6. Graph showing summary statistics of rainfall characteristics and antecedent conditions for individual

storms in the lower Charles River Watershed during Water Year 2000 and at Logan International Airport,

Boston, from 1970 to 1995

7. Photograph showing upstream view of footbridge located at U.S. Geological Survey gaging station

Charles River at Watertown (01104615)

8. Graph showing flow-duration curves of simulated 15-minute flow values for tributary and uniform

land–use subbasins, and the flow–duration curve of observed 15–minute flow values at Charles River

at Watertown (01104615), lower Charles River Watershed, Water Year 2000

9–14.Photographs showing U.S. Geological Survey gaging station:

9.Single-family land use (01104630), Newton Center, ( A ) upstream and ( B ) downstream views

10.Laundry Brook (01104640), Watertown, ( A ) upstream and ( B ) downstream views

11.Faneuil Brook (01104660), Brighton, ( A ) upstream view and ( B ) above manhole

12.Multifamily land use ( 01104673), Cambridge

13.Commercial land use (01104677), Cambridge

14.Muddy River (01104683), Brookline, upstream views

15.Map showing location of the U.S. Geological Survey (USGS) gaging station at Stony Brook (01104687),

along the Stony Brook, lower Charles River Watershed

16, 17.Photographs showing U.S. Geological Survey:

16.Gaging station Stony Brook (01104687), Boston

17.Water-quality sampling station Charles River at Boston Science Museum (01104710), ( A ) upstream

and ( B ) downstream views

18–20.Graphs showing:

18.Comparison between stormwater event mean concentrations measured in samples from the lower

Charles River Watershed, Water Year 2000, and stormwater concentrations from other studies

19.Characteristic stormwater hydrograph and pattern of fecal coliform bacterial density before, during,

and after a storm at U.S. Geological Survey gaging station Charles River at Watertown

(01104615), lower Charles River Watershed, July 26–30, 2000

20.Goodness of fit between measured and predicted event mean concentrations of fecal coliform

bacteria at two U.S. Geological Survey gaging stations in the lower Charles River Watershed

21.Maps showing spatial distribution of annual loads by tributary subbasin, lower Charles River Watershed,

Water Year 2000

22.Hyetograph showing the 3-month design storm (hourly) and 1-year design storm (21 minutes), lower

Charles River Watershed

23.Diagram showing a typical combined sewer

24, 25.Graphs showing:

24.Changes in constituent loads after sewer separation relative to pre-separation loads in the Stony

Brook Subbasin, lower Charles River Watershed

25.Average daily loading intensity of fecal coliform bacteria from upstream and selected tributary

subbasins, lower Charles River Watershed, Water Year 2000

TABLES

1.Locations and USGS station numbers used in the study, lower Charles River Watershed, Massachusetts

2.Analytes, laboratories, and analytical techniques used in this study

3.Discharge at the time of sampling (dry weather) or total stormwater volume (stormwater), lower

Charles River Watershed, Water Year 2000

4.Annual dry-weather and stormwater-discharge volumes and yields upstream and from tributary

subbasins to the lower Charles River Watershed, Water Year 2000

5.Characteristics of storms sampled during this study of the lower Charles River Watershed, storms recorded

at Logan Airport National Weather Service station between 1970 and 1995, and Massachusetts Water

Resources Authority design storms

6.Constituent loads for sampled storms, lower Charles River Watershed

7.Stormwater volume for 3-month and 1-year design storms, lower Charles River Watershed

8.Contamination bias expected in 10 percent of the environmental samples collected during the study of the

lower Charles River Watershed

9.Standard deviations of replicate samples collected in this study of the lower Charles River Watershed

10.Sources and environmental importance of selected constituents and water-quality properties

11.Results of Sign Test between paired stormwater event mean concentrations (EMCs) for sampled storms

at uniform land-use stations, lower Charles River Watershed

12.Characteristics of selected major and trace elements of potential interest to studies of urban and highway

runoff

13.Summary statistics for selected stormwater constituents from other studies

14.Percentages of dry-weather, stormwater, and total loads of each constituent contributed to the lower

Charles River at each station in the lower Charles River Watershed, Water Year 2000

15.Percentages of dry-weather and stormwater loads of each constituent at each station in the lower Charles

River Watershed, Water Year 2000

16.Land use in the lower Charles River Watershed

17.Constituent yields for 3-month and 1-year design storms, and Water Year 2000, lower Charles River

Watershed

18.Estimated volume of combined sewage overflow to Stony Brook, lower Charles River Watershed

19.Mean concentrations of selected constituents and water-quality properties in combined sewage

20.Projected constituent event mean concentrations for Stony Brook, lower Charles River Watershed, under

conditions of complete sewer separation

21.Estimated stormwater loads to Stony Brook after sewer separation for design storms and Water Year

2000, lower Charles River Watershed

22.Dry-weather constituent concentrations and physical properties measured between July 1999 and July

2000, lower Charles River Watershed

23.Event mean concentrations of stormwater constituents and water-quality properties measured between

January 2000 and September 2000, lower Charles River Watershed

24.Bacterial densities in discrete stormwater samples collected between January 2000 and September 2000,

lower Charles River Watershed

25.Statistical summary for constituents and water-quality properties of dry-weather and stormwater

flow-composite samples measured between July 1999 and September 2000, lower Charles River Watershed

26.Regression coefficients of models used to estimate event mean concentrations from storm-rainfall characteristics and antecedent conditions, lower Charles River Watershed

27.Constituent loads for Water Year 2000 stormwater, Water Year 2000 dry-weather conditions, and 3-month and 1-year design storms, lower Charles River Watershed



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The citation for this report, in USGS format, is as follows:

Breault, R.F., Sorenson, J.R. and Weiskel, P.K., 2002, Streamflow, Water Quality, and Contaminant Loads in the Lower Charles River Watershed, Massachusetts, 1999–2000: U.S. Geological Survey Water-Resources Investigations Report 02-4137, 139 p.


 For more information about USGS activities in Massachusetts-Rhode Island District, visit the USGS Massachusetts-Rhode Island Home Page.


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